Wake-up trigger using MEMS wind turbines

ABSTRACT

A portable device includes micro-electro-mechanical systems (“MEMS”) wind turbines integrated in the portable device. A gesture detection module receives signals generated by the MEMS wind turbines based on movement of the portable device that causes a wind force to be applied to the MEMS wind turbines. The gesture module then recognizes a gesture based on the signals generated from the wind force and initiates an action of the portable device that corresponds to the gesture (e.g., the device is awakened).

TECHNICAL FIELD

The present disclosure is related generally to mobile communicationsdevices and, more particularly, to detecting user gestures on suchdevices.

BACKGROUND

Portable devices, such as mobile phones, tablet devices, digitalcameras, wearable devices, and other types of computing and electronicdevices can be used in a variety of ways. Further, users can provideinput in a variety of ways, such as by pressing a button, swiping atouch screen, giving a voice command, and so on. Conventionally, theseportable devices required the user to press a button to turn on or wakeup the device prior to enabling the user to execute an application orotherwise operate the device. For example, when a user's phone receivesan incoming call, the user is generally required to press a button orswipe the touch screen to answer the call. In some instances, the usermay have difficulty answering the phone, such as when attempting toswipe the touch screen with a wet finger or failing to properly pressthe button such that the device fails to connect the call. Further,conventional portable devices can be difficult to operate with the samehand that is holding the device, which many users attempt to do whilethey are multi-tasking. These difficulties can lead to missed calls or apoor user experience, resulting in user frustration.

In addition, gestures are becoming more common among portable devices asa way for users to provide input. For example, some touch-screen devicescan recognize different swipe directions as corresponding to differentcommands. Generally, however, touch-screen devices require that thetouch screen be powered on to enable the device to recognize thegesture.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

While the appended claims set forth the features of the presenttechniques with particularity, these techniques, together with theirobjects and advantages, may be best understood from the followingdetailed description taken in conjunction with the accompanying drawingsof which:

FIG. 1 illustrates an example portable device in which embodiments ofusing micro-electro-mechanical systems (“MEMS”) wind turbines forgesture detection or as a wake-up trigger can be implemented;

FIG. 2 illustrates example sensor configurations in which embodiments ofusing MEMS wind turbines for gesture detection or as a wake-up triggercan be implemented;

FIG. 3 further illustrates examples of sensor configurations in whichembodiments of using MEMS wind turbines for gesture detection or as awake-up trigger can be implemented;

FIG. 4 illustrates example methods of gesture detection using MEMS windturbines in accordance with one or more embodiments;

FIG. 5 illustrates example methods of a wake-up trigger using MEMS windturbines in accordance with one or more embodiments; and

FIG. 6 illustrates various components of an example device that canimplement embodiments of using MEMS wind turbines for gesture detectionor as a wake-up trigger.

DETAILED DESCRIPTION

Embodiments of using MEMS wind turbines for gesture detection or as awake-up trigger are described, such as for any type of portable device.Typically, gestures are recognized as a user touching the screen in acertain manner or swiping the screen in a particular direction. Othergestures can be recognized using infra-red sensors to detect movement ofa user or the user's hand, for example. However, a portable device suchas a mobile device, for example, can fail to recognize some gestures,such as when the user's finger is wet, which interferes with the tactileconnection between the user's finger and the touch screen. Additionalchallenges arise when a user attempts to perform a gesture with the samehand that is holding the mobile device.

A MEMS wind turbine is a miniature wind turbine that generateselectrical energy. The MEMS wind turbine can be integrated in a portabledevice such that air flowing substantially parallel to a plane formed bythe blades of the MEMS wind turbine causes the MEMS wind turbine torotate. Alternatively, the MEMS wind turbine can be integrated with theportable device such that air flowing substantially perpendicular to aplane formed by the blades of the MEMS wind turbine can cause the MEMSwind turbine to rotate. In implementations, the MEMS wind turbines canbe formed from two-dimensional pieces utilizing planar multilayerelectroplating techniques assembled into a three-dimensional structure.

In aspects of gesture detection using MEMS wind turbines, a portabledevice can be implemented to recognize a gesture based on sensory inputgenerated by the MEMS wind turbines. For example, when a user lifts theportable device to answer a phone call, wind forces cause some of theMEMS wind turbines to rotate and generate a signal. Then, based on thesignal generated by the MEMS wind turbines, the portable device can wakeup a display device of the portable device or automatically connect thecall for the user, without requiring additional user interaction, suchas a button-press, a screen-swipe, and so on.

In implementations of a wake-up trigger using MEMS wind turbines, aportable device is implemented to determine movement based on signalsgenerated by the MEMS wind turbines. For example, when a user lifts theportable device from the user's waist up to near the user's face (orjust generally moves the device up), the display device can be turned onautomatically. In implementations, a state change can be triggered toinitiate power to components of the portable device, such as the displayscreen, a microphone, and so on. The state change effectively wakes upthe components, such as from a sleep state, a hibernating state, an offstate, and so on. In this way, movement of the portable device can causethe portable device to wake up, without the use of accelerometers orgyroscopes, and without additional user interaction. For example, theportable device can be in a state that is not drawing any power, andthen the portable device can be lifted or moved in such a way togenerate wind sufficient to activate the MEMS wind turbines, which cantrigger the portable device, or components of the portable device, to beturned on.

While features and concepts of using MEMS wind turbines for gesturedetection or as a wake-up trigger can be implemented in any number ofdifferent devices, systems, environments, or configurations, embodimentsof using MEMS wind turbines for gesture detection or as a wake-uptrigger are described in the context of the following example devices,systems, and methods.

FIG. 1 illustrates an example portable device 100 in which embodimentsof using MEMS wind turbines for gesture detection or as a wake-uptrigger can be implemented. The example portable device 100 may be anytype of mobile device (e.g., mobile phone, tablet device, digitalcamera, and so on), wearable device (e.g., watch, glasses, bracelet,hearing aid-like device, and any other item that is wearable by a userand which has electronic or computing technologies incorporatedtherein), or other types of computing and electronic devices that aretypically battery powered. In this example, the portable device 100includes a variety of hardware components, examples of which include aprocessing system 102, an example of a computer-readable storage mediumillustrated as a memory device 104, a power controller 106, and so on.The processing system 102 is representative of functionality to performoperations through execution of instructions stored in the memory device104. Although illustrated separately, functionality of these componentsmay be further divided, combined (e.g., on an application-specificintegrated circuit), and so forth. The portable device 100 can includesensors 108 that detect movement of the portable device 100 and providesensor inputs 110 to the components of the portable device 100. Inembodiments, the sensors 108 are implemented as MEMS wind turbines, asshown and described below with reference to FIGS. 2 and 3. Additionally,the processing system 102 includes a gesture module 112 for detectinggestures of a user of the portable device 100 based on the sensor inputs110 from the sensors 108. Also illustrated is the power controller 106including controller logic 114 and a controller circuit 116 that arefurther described below with reference to features of the wake-uptrigger.

The gesture module 112 represents functionality of the portable device100 to recognize a variety of different gestures from sensory inputgenerated by the sensors 108 and to then initiate an action of theportable device 100 that corresponds to the gesture. For example, thegesture module 112 can determine a change in orientation of the portabledevice 100 and initiate a corresponding change to a user interfacedisplayed on a display device of the portable device 100. In anadditional example, the gesture module 112 can determine that theportable device 100 is being lifted while the portable device 100 isreceiving an incoming call, such as a phone call, a text message, aninstant message, and so on, and can automatically initiate connectingthe call. Other examples include determining that the portable device100 is being positioned to initiate a phone call and initiating adisplay of a user interface that is configured to enable the user toinitiate the phone call. Thus, the gesture module 112 can recognize anyof a variety of different gestures and initiate a corresponding actionof the portable device 100. These examples are illustrated asnon-exclusive examples of the functionality provided by the gesturemodule 112 and are not intended to be limiting in any way.

The portable device 100 includes the power controller 106 that isimplemented to initiate a state change of one or more components of theportable device 100. The power controller 106 is implemented to receivesignals as a sensor input 110 from the sensors 108, and then thecontroller logic 114 initiates the controller circuit 116 to implement astate change of the one or more components. In implementations, thepower controller 106 can be implemented with hardware components whichcan be activated while a processor of the portable device 100 is in anoff state.

Additionally, the portable device 100 can be implemented with any numberand combination of differing components as further described withreference to the example device shown in FIG. 6. As an alternative tohardware components, the power controller 106 can be implemented as asoftware application or module, such as executable software instructions(e.g., computer-executable instructions) that are executable with theprocessing system 102 of the device 100. The power controller 106 can bestored on computer-readable storage memory (e.g., the memory device104), such as any suitable memory device or electronic data storageimplemented in the portable device 100. In practice, the powercontroller 106 may be implemented in software as part of an operatingsystem of the portable device 100. Additionally, a separatemicrocontroller may be implemented to process the power controller 106as software.

In this example, the power controller 106 includes a controller circuit116 that switches states of various components of the portable device100. The power controller 106 also includes controller logic 114 thatcontrols the controller circuit 116. As with the power controller 106,the controller logic 114 may be implemented in hardware, software, or asa combination thereof.

The portable device 100 also includes the one or more sensors 108, whichmay be implemented as MEMS wind turbines. The MEMS wind turbines can beintegrated in the portable device 100 in any of a variety of ways. Forexample, the MEMS wind turbines can be recessed in a housing of theportable device 100 and within a channel that allows air flow. Movementof the portable device 100 can cause air to flow through the channel andover the MEMS wind turbines causing the MEMS wind turbines to rotate andgenerate a signal. Further discussion of this and other aspects isprovided below.

FIG. 2 illustrates an example 200 of a sensor configuration in whichembodiments of using MEMS wind turbines for gesture detection or as awake-up trigger can be implemented. As shown in the example 200, theportable device 100 includes MEMS wind turbines 202 that act as sensorsto detect air flow (e.g., wind 204) caused by movement of the portabledevice 100. In implementations, the MEMS wind turbines 202 are examplesof the sensors 108 that detect movement of the portable device 100, asdescribed above with reference to FIG. 1. As the wind 204 passes overthe MEMS wind turbines 202, associated wind forces can cause the MEMSwind turbines 202 to rotate and generate a signal (e.g., as a sensorinput 110 to other components of the portable device 100). The signalcan be in any of a variety of forms, such as a voltage, for example. Asshown in FIG. 2, the MEMS wind turbines 202 can be recessed within ahousing 206 of the portable device 100, such as within a channel thatallows air to pass through. In implementations, the MEMS wind turbines202 can be located on the back, front, or along the sides of the housing206 of the portable device 100. Further, the MEMS wind turbines 202 canbe integrated at any location on the portable device 100 that issuitable to allow wind forces to initiate rotation of the MEMS windturbines 202.

FIG. 3 illustrates additional examples 300 of various sensorconfigurations in which embodiments of using MEMS wind turbines forgesture detection or as a wake-up trigger can be implemented. Inimplementations, the MEMS wind turbines 202 can be integrated in theportable device 100 in various locations. For example, the MEMS windturbines 202 can be disposed on one or more sides of the portable device100 (e.g., integrated in the housing 206), such as shown in an example302. The MEMS wind turbines 202 can be recessed within the housing 206of the portable device 100 along one or more sides of the device. Asshown in an example 304, the MEMS wind turbines 202 can be located at ornear the corners of the housing of the portable device 100. Inimplementations, the recessed portion of the portable device 100 can beangled at the corner to allow one or more of the MEMS wind turbines 202to be integrated thereon. In addition, the housing 206 can include aperforated surface 306 over the MEMS wind turbines 202, where theperforations (e.g., holes or partial openings) in the surface allow windto pass through and over the MEMS wind turbines 202. Any of a variety ofconfigurations of perforations can be used, such as, for example,configurations 308 or 310.

Generally, any services, components, modules, methods, or operationsdescribed herein can be implemented using software, firmware, hardware(e.g., fixed-logic circuitry), manual processing, or any combinationthereof. Some operations of the example methods may be described in thegeneral context of executable instructions stored on computer-readablestorage memory that is local or remote to a computer processing system,and implementations can include software applications, programs,functions, and the like. Any of the functionality described herein canbe performed, at least in part, by one or more hardware logiccomponents, such as, and without limitation, field-programmable gatearrays, application-specific integrated circuits, application-specificstandard products, system-on-a-chip systems, complex programmable logicdevices, and the like.

FIG. 4 illustrates example methods 400 of gesture detection using MEMSwind turbines. The order in which the method is described is notintended to be construed as a limitation, and any number or combinationof the described method operations can be performed in any order toperform a method or an alternate method.

At 402, sensor data are received from MEMS wind turbines that areintegrated in a portable device. For example, as the portable device islifted or otherwise moved, such as from the user's waist level to theuser's head level, a relatively small wind force is generated inrelation to the portable device. Depending on an orientation of theportable device when moving through the air, some of the MEMS windturbines 202 may generate a signal while others do not. For example, thewind force may cause MEMS wind turbines near a top corner of theportable device to rotate without affecting MEMS wind turbines locatednear a bottom corner. As an alternative example, MEMS wind turbineslocated near a first corner can generate a first signal based on thewind force, while other MEMS wind turbines near a second corner of theportable device generate a second signal, such as a counter-signal, thatcan be used in connection with the first signal. Accordingly,differences in sensor data or counter-signals generated by differentMEMS wind turbines on the portable device can be used to determine avariety of different information, such as device orientation inthree-dimensional space, context of a user using the portable device,gestures or input to perform a function of the portable device, and soon.

At 404, a signal strength of the sensor data is measured. This step canbe performed in any suitable way. For example, the gesture module 112that is implemented in the portable device 100 can measure the signalstrength of the sensor data generated by the MEMS wind turbines 202. At406, a determination is made as to whether the signal strength of thesensor data exceeds a threshold value that represents a likelihood thatthe portable device 100 is being moved. For example, the threshold valuecan be used to determine whether the portable device 100 wasinadvertently bumped or moved, or whether the portable device 100 wasintentionally moved as part of a gesture. In an additional example, thethreshold can be used to determine the difference between a gesturebeing performed and the user walking or running Δny suitable thresholdvalue can be used, such as a predefined static threshold, a dynamicallyadjustable threshold (e.g., a threshold based on machine learning of thedevice's characteristic motions), multiple thresholds, or anycombination thereof. In implementations, the threshold can include aduration of time over which the sensor input is continuously received.

At 408, a gesture is recognized based on the sensor data generated fromthe wind force. For example, the gesture module 112 that is implementedin the portable device 100 can utilize the sensor data generated by theMEMS wind turbines 202 and received as the sensor inputs 110 torecognize a gesture. Any of a variety of gestures can be recognized.Some examples include, but are not limited to, the portable device 100being lifted to answer an incoming phone call, positioned to initiate aphone call, lowered after a phone call is disconnected, oriented tochange an orientation of the portable device 100, and so on.

At 410, an action of the portable device 100 that corresponds to thegesture is initiated responsive to recognizing the gesture. For example,based on the gesture, the gesture module 112 can initiate any of avariety of different actions of the portable device 100. Some examplesinclude, but are not limited to, connecting the incoming phone call,initiating a display of a user interface configured to enable the userto initiate the phone call, turning off a display device of the portabledevice 100, changing an orientation of the user interface displayed onthe display device of the portable device 100, initiating mute,initiating silent mode or airplane mode, and so on.

FIG. 5 illustrates example methods 500 of using MEMS wind turbines as awake-up trigger. The order in which the method is described is notintended to be construed as a limitation, and any number or combinationof the described method operations can be performed in any order toperform a method or an alternate method.

At 502, one or more signals are received based on a wind force appliedto MEMS wind turbines. For example, the power controller 106 that isimplemented in the portable device 100 receives signals (e.g., sensorinputs 110) generated by the sensors 108 (e.g., MEMS wind turbines 202).The signals can be generated by the MEMS wind turbines 202 based on awind force effective to initiate rotation of at least some of the MEMSwind turbines 202.

At 504, the portable device is determined to be moving based on the oneor more signals generated from the wind force. For example, the powercontroller 106 can determine that the sensor inputs 110 from the MEMSwind turbines 202 are continuously sufficient to exceed a duration oftime or a threshold signal strength that indicates a likelihood ofmovement of the portable device 100.

At 506, a state change is triggered to initiate power to one or morecomponents of the portable device 100 effective to wake up the one ormore components. For example, the power controller 106 can, based on thedetermination that the portable device 100 is moving, initiate power toturn on a display device, a microphone, an audio system, or any othercomponent of the portable device 100. In implementations, an interruptsignal can be sent to the processing system to initiate power to any ofthe components.

FIG. 6 illustrates various components of an example device 600 in whichembodiments of using MEMS wind turbines for gesture detection or as awake-up trigger can be implemented. The example device 600 can beimplemented as any of the computing devices described with reference tothe previous FIGS. 1 through 5, such as any type of client device,mobile phone, tablet, computing, communication, entertainment, gaming,media playback, wearable, or other type of device. For example, theportable device 100 shown in FIG. 1 may be implemented as the exampledevice 600.

The device 600 includes communication transceivers 602 that enable wiredor wireless communication of device data 604 with other devices.Additionally, the device data 604 can include any type of audio, video,or image data. Example transceivers include wireless personal areanetwork radios compliant with various IEEE 802.15 standards, wirelesslocal area network radios compliant with any of the various IEEE 802.11standards, wireless wide area network radios for cellular phonecommunication, wireless metropolitan area network radios compliant withvarious IEEE 802.15 standards, and wired local area network Ethernettransceivers for network data communication.

The device 600 may also include one or more data input ports 606 viawhich any type of data, media content, or inputs can be received, suchas user-selectable inputs to the device 600, messages, music, televisioncontent, recorded content, and any other type of audio, video, or imagedata received from any content or data source. The data input ports mayinclude universal serial bus ports, coaxial cable ports, and otherserial or parallel connectors (including internal connectors) for flashmemory, digital versatile discs, compact discs, and the like. These datainput ports 606 may be used to couple the device 600 to any type ofcomponents, peripherals, or accessories such as microphones or cameras.

The device 600 includes a processing system 608 of one or moreprocessors (e.g., any of microprocessors, controllers, and the like) ora processor and memory system implemented as a system-on-chip thatprocesses computer-executable instructions. The processor system may beimplemented at least partially in hardware, which can include componentsof an integrated circuit or on-chip system, an application-specificintegrated circuit, a field-programmable gate array, a complexprogrammable logic device, and other implementations in silicon or otherhardware. The device 600 can be implemented with any one or combinationof software, hardware, firmware, or fixed-logic circuitry that isimplemented in connection with processing and control circuits, whichare generally identified at 610. The device 600 may further include anytype of a system bus or other data and command transfer system thatcouples the various components within the device. A system bus caninclude any one or combination of different bus structures andarchitectures, as well as control and data lines.

The device 600 also includes computer-readable storage memory 612 thatenables data storage, such as data-storage devices that can be accessedby a computing device 600, and that provide persistent storage of dataand executable instructions (e.g., software applications, programs,functions, and the like). Examples of the computer-readable storagememory 612 include volatile memory and non-volatile memory, fixed andremovable media devices, and any suitable memory device or electronicdata storage that maintains data for computing device access. Thecomputer-readable storage memory can include various implementations ofrandom-access memory, read-only memory, flash memory, and other types ofstorage media in various memory-device configurations. The device 600may also include a mass-storage media device.

The computer-readable storage memory 612 provides data-storagemechanisms to store the device data 604, other types of information ordata, and various device applications 614 (e.g., software applications).For example, an operating system 616 can be maintained as softwareinstructions within a memory device and executed by the processingsystem 608. The device applications 614 may also include a devicemanager, such as any form of a control application, softwareapplication, signal-processing and control module, code that is nativeto a particular device, a hardware abstraction layer for a particulardevice, and so on. In this example, the device 600 includes a gesturemodule 618 that implements embodiments of gesture detection using MEMSwind turbines and includes controller logic 620 that implementsembodiments of wake-up triggers using MEMS wind turbines. The gesturemodule 618 and the controller logic 620 may be implemented with hardwarecomponents or in software, such as when the device 600 is implemented asthe portable device 100 described with reference to FIGS. 1 through 5.An example of the gesture module 618 is the gesture module 112 that isimplemented by the portable device 100, and an example of the controllerlogic 620 is the controller logic 114 that is also implemented by theportable device 100.

The device 600 also includes an audio or video processing system 622that generates audio data for an audio system 624 or generates displaydata for a display system 626. The audio system or the display systemmay include any devices that process, display, or otherwise renderaudio, video, display, or image data. Display data and audio signals canbe communicated to audio component or to a display component via aradio-frequency link, S-video link, high-definition multimediainterface, composite-video link, component-video link, digital videointerface, analog audio connection, or other similar communication link,such as media data port 628. In implementations, the audio system or thedisplay system are integrated components of the example device 600.Alternatively, the audio system or the display system are external,peripheral components to the example device 600.

The device 600 can also include one or more power sources 630, such aswhen the device 600 is implemented as a portable device. The powersources 630 may include a charging or power system, and can beimplemented as a flexible-strip battery, a rechargeable battery, acharged super-capacitor, or any other type of active or passive powersource.

In view of the many possible embodiments to which the principles of thepresent discussion may be applied, it should be recognized that theembodiments described herein with respect to the drawing figures aremeant to be illustrative only and should not be taken as limiting thescope of the claims. Therefore, the techniques as described hereincontemplate all such embodiments as may come within the scope of thefollowing claims and equivalents thereof.

We claim:
 1. A method for detecting a wake-up trigger for a portabledevice, the method comprising: receiving a signal based on a wind forceapplied to micro-electro-mechanical systems (“MEMS”) wind turbines thatare integrated in the portable device proximate to one another within arecessed channel of the portable device, the wind force applied based onmovement of the portable device; receiving the signal generated from thewind force as an indicator that the portable device is moving; and basedon the indicator that the portable device is moving, triggering a statechange to initiate power to a component of the portable device effectiveto wake up the component.
 2. The method of claim 1 wherein the statechange is triggered by an interrupt signal sent to a processor of theportable device.
 3. The method of claim 1 wherein the state change istriggered by waking-up the portable device from a sleep state.
 4. Themethod of claim 1 wherein the state change is triggered by turning onthe portable device from an off state.
 5. The method of claim 1 whereinthe state change activates a microphone.
 6. The method of claim 1wherein the state change turns on a display device.
 7. The method ofclaim 1 wherein the signal generated from the wind force includes aswitch signal that represents actuation of a power button of theportable device.
 8. The method of claim 1 wherein the MEMS wind turbinesare recessed below a surface of a housing of the portable device.
 9. Themethod of claim 1 wherein the indicator that the portable device ismoving is based on the signal generated from the wind force having asignal strength that exceeds a threshold value.
 10. A portable devicecomprising: micro-electro-mechanical systems (“MEMS”) wind turbinesintegrated in the portable device, the MEMS wind turbines including asubset of the MEMS wind turbines disposed proximate to one anotherwithin a recessed channel of the portable device; and a memory andprocessing system to implement a power controller that is configured to:receive a signal generated by the MEMS wind turbines based on movementof the portable device that causes a wind force to be applied to theMEMS wind turbines, the signal received as an indicator that theportable device is moving; and based on the indicator that the portabledevice is moving, trigger a state change to initiate power to acomponent of the portable device effective to wake up the component. 11.The portable device of claim 10 wherein the state change is triggered byan interrupt signal sent to a processor of the portable device.
 12. Theportable device of claim 10 wherein the state change is triggered by theportable device being turned on from an off state.
 13. The portabledevice of claim 10 wherein the state change is triggered by the portabledevice waking up from a hibernating state.
 14. The portable device ofclaim 10 wherein the state change turns on a display device.
 15. Theportable device of claim 10 wherein the signal generated from the windforce includes a switch signal that represents actuation of a powerbutton of the portable device.
 16. The portable device of claim 10wherein the MEMS wind turbines are recessed below a surface of a housingof the portable device.
 17. The portable device of claim 10 wherein theindicator that the portable device is moving is based on the signalgenerated from the wind force having a signal strength that exceeds athreshold value.
 18. A system comprising: micro-electro-mechanicalsystems (“MEMS”) wind turbines integrated in a portable device andconfigured to generate a signal based on wind forces applied to the MEMSwind turbines, the wind forces caused by movement of the portabledevice, two or more of the MEMS wind turbines having separate rotationalaxes and being disposed proximate to one another within a recessedchannel of a housing of the portable device; a memory and processingsystem to implement a power controller that is configured to: receivethe signal generated based on the wind forces caused by the movement ofthe portable device, the signal received as an indicator that theportable device is moving; and responsive to the indicator that theportable device is moving, trigger a state change to initiate power to acomponent of the portable device effective to wake up the component. 19.The system of claim 18 wherein the state change is triggered by theportable device waking up from a sleep state.
 20. The system of claim 18wherein the signal generated from the wind force includes a switchsignal that represents actuation of a power button of the portabledevice.